Application of Ewald summations to long-range dispersion forces

COMP 6

Pieter J. In 't Veld, Ahmed E. Ismail, aismail@sandia.gov, and Gary S. Grest, gsgrest@sandia.gov. PO Box 5800, Sandia National Laboratories, Albuquerque, NM 87185
We present results illustrating the effects of using explicit summation terms for the r-6 dispersion term on the interfacial properties of a Lennard-Jones fluid and SPC/E water. For the Lennard-Jones fluid, we find that the use of long-range summations, even with a short "crossover radius," yields results that are consistent with simulations using large cutoff radii. Simulations of SPC/E water demonstrate that the long-range dispersion forces are of secondary importance to the Coulombic forces. In both cases, we find that the ratio of box size L|| to crossover radius rck plays an important role in determining the magnitude of the long-range dispersion correction, although its effect is secondary when Coulombic interactions are also present. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract No. DE-AC04-94AL85000.